Meniscus tear

Definitions & Key takeaways

Meniscus tear is when one or both of the menisci of the knee joint are torn. Acute tears usually occur in athletes during contact sports, when the menisci are violently compressed. Chronic tears can also occur, often in older people due to wear and tear changes of menisci. Symptoms include pain, swelling, and stiffness, and the diagnosis is mainly based on clinical symptoms, physical exam with an MRI for confirmation. Treatment can be conservative, or by open or arthroscopic surgery.

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Introduction0:00–0:23

The menisci are crescent shaped fiber cartilage cushions found in the knee joint. Normally there is the medial and lateral menisci between the femur and tibia.
So a meniscus tear more commonly known as a torn knee cartilage is when one of the menisci of the knee is torn. This usually occurs during a trauma during contact sports.
The knee is a complex joint, actually, it's a combination of three joints. These are the femoropatellar joints between the femur and patella and the two tibiofemoral joints, which are formed by the bony prominences, also called the condyles of the tibia and femur between the femoral and tibial condyles.

Physiology0:23–1:47

There are the medial and lateral menisci. The menisci act to absorb compressive force which can reach up to three times the body weight while walking.
In addition, the menisci have a cup shaped surface which provides a deeper place for the condyles to fit in improving joint stability.
Next, the knee joint is supported by a number of ligaments. So within the joint space, there's the anterior cruciate ligament or ACL which runs from the anterior middle edge of the tibia to the lateral condyles of the femur and the posterior cruciate ligament or PCL that runs from the middle, posterior edge of the tibia to the medial condyle of the femur.
Now, outside the joint space, we've got one collateral ligament between the femur and the tibia on each side of the joint which are the lateral collateral ligament or LCL and the medial collateral ligament or MCL.
The MCL is firmly attached to the medial meniscus which makes it less mobile compared to the lateral meniscus. A meniscus tear can occur when the meniscus is violently compressed, called an acute tear, which usually occurs in young athletes, acute tears typically occur when the knee is bent and at the same time excessively twisted like when you're playing basketball and then you suddenly change direction trying to cross over another player.

Pathology1:47–3:13

Acute meniscus tears can also occur as part of an unhappy triad injury. This is where a lateral force to the knee like when the knee is hit by a hockey puck causes tears in the ACL MCL and one of the menisci.
Now, regarding which of the menisci, it's worth mentioning that even though the classic unhappy triad consists of the ACL MCL and medial meniscus tears, the lateral meniscus is more commonly injured than the medial.
This is because when the knee is affected by a blow from the lateral side, the lateral meniscus gets compressed between the tibia and the femur leading to injury.
In contrast to an acute tear, there are also chronic tears which usually occur in older people. This is because the wear and tear of the menisci make them more susceptible to tears with minimal force or any noticeable trauma.
An elderly person might tear their meniscus from simply getting up from a chair. All right, let's talk about symptoms and an acute tear.

Symptoms3:13–3:47

There can be an intense pain in the joint at the time of trauma over the next 24 hours, joint pain and swelling increase gradually.
In addition, a piece of the torn meniscus can get stuck between the condyles, restricting joints movement called joint locking.
This causes a clicking sound or a popping sensation when trying to extend the knee. In contrast to acute tears, pain in chronic tears can be absent.
However, mechanical symptoms like joint locking or popping sensation can still be present. The diagnosis of meniscus tear is mainly based on clinical symptoms.

Diagnosis3:47–4:58

In addition to testing knee joint range of motion and any associated pain. One of the tests used to do that is mcmurray test where the knee is bent, internally rotated and then extended in order to compress the lateral meniscus.
If the person feels pain while extending the knee, there is likely a lateral meniscus tear. The same is done to diagnose a medial meniscus tear where the knee is bent externally rotated and then extended to compress the medial meniscus.
An X ray can't directly show a meniscus tear but it can show degenerative changes in the joint like those in osteoarthritis which are commonly found in cases of chronic tears.
Examples of osteoarthritic changes are joint space narrowing, osteophytes formation, which are small bony projections and subchondral sclerosis which means hardening of the bones that underlie the joint cartilage.
However, the diagnosis of acute and chronic meniscus tears can be confirmed using an MRI which will not only show the tear but also the size and location.

Treatment4:58–5:20

The treatment of meniscus tear begins with ice to reduce inflammation, rest and pain medication. Also, physical therapy can strengthen the muscles around the knee which helps decreasing the load on the menisci.
In more severe cases, open or arthroscopic surgery may be needed to repair the torn meniscus. All right, as a quick recap, meniscus tear is when one or both of the menisci of the knee joint are torn.

Review5:20–5:51

Acute tears usually occur in athletes during contact sports when the menisci are violently compressed. On the other hand, chronic tears occur in older people and are due to wear and tear changes of the menisci.
The diagnosis is mainly based on clinical symptoms like knee pain and swelling and can be confirmed by MRI. Treatment can be conservative or by open or arthroscopic surgery.